DSM2 vs AFHSS and FASST for Range

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DSM2 vs AFHSS and FASST for Range

Postby Jumpjet » Sat Jun 05, 2010 10:41 pm

Who has first hand experience with range, flying FPV with DSM2, AFHSS, and FASST systems? I known that DSM2 only uses 2 channels but at a higher power level. So I assume that means that you'll get better range using DSM2, right? The other systems are great for protecting you from interference but uses less power on each freq which I assume would give you a reduced range.

Has anyone done a range comparison with these systems? I am thinking about getting the Aurora 9 which uses AFHSS. I know some of you are going to say get out of the 2.4 band because 72MHz is still better for FPV, but I just wanted to know the best 2.4 system for range.

I currently use a DX7 with a AR7000rx and my best range has been 4 miles. I can usually average 2 miles without any problems.
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Re: DSM2 vs AFHSS and FASST for Range

Postby RCModelReviews » Sun Jun 06, 2010 12:13 am

There are a *lot* of variables which affect the range of a system.

For instance, if you simply compare the raw range of various systems it's quite possible that you'll get completely different results once you repeat the test with a powerful out-of-band video transmitter nearby. That's because some 2.4GHz RC receivers are better at rejecting those out-of-band signals than others.

For what it's worth, I see someone tested the FrSky system out to 5.5Kms and it was still going strong.

What I hope to do in a month or two's time is to set up one of my UAV models to simply fly off into the distance with several receivers onboard, hooked up to some data-logging equipment. That will register the exact distance at which failsafe starts to kick in and it will be a true, accurate indication of actual ground to air range.
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Re: DSM2 vs AFHSS and FASST for Range

Postby Jumpjet » Sun Jun 06, 2010 10:24 am

RCModelReviews,

I understand that there are a lot of variables that will affect range of a system. But I'm just wondering in an equal environment with a DSM2 and AFHSS, which would give the best range. I hear DSM2 would give better range because it uses a wideband, is that correct?

BTW, I watched your videos on the AFHSS and DSM2 and found them very interesting but still left me with this question about range.
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Re: DSM2 vs AFHSS and FASST for Range

Postby RCModelReviews » Sun Jun 06, 2010 8:41 pm

All I can tell you is that both systems (in my testing) have in excess of 1.5kms (almost 1 mile) of range and that both systems have been tested by others out to ranges in excess of 3 miles. If anyone can see a model well enough to control it at those distances without FPV then they're doing very well.

I would say that, because they take two different approaches (dual DSSS versus constantly agile DSSS), the winner would depend on the conditions.

It would be easy to come up with a situation where AFHSS wins and just as easy to come up with a situation where DSM2 wins.

In a relatively static environment the DSM2 system may win but if there's any amount of variation in the noise profile of the band, the AFHSS may come out better.

And remember that the sensitivity of the receiver plays an huge part in determining range. The Hitec receivers are more sensitive (in my tests) than most of the DSM2 receivers so that immediately negates any extra power that the DSM2 system may have. In fact, there appears to be a significant variation in the sensitivity of the various Spektrum models of DSM2 receivers.
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Re: DSM2 vs AFHSS and FASST for Range

Postby Mr Ed » Thu Jul 29, 2010 12:24 am

I have an Airtronics SD 10G and from the factory testing it has a range of 5 miles using the 10 channel FHSS 3 receiver. I do believe that that kind of range is going to be line of sight and under perfect conditions and more then likely not what you will see in the real world. I have no idea how they did their testing, but I also don't believe that you are going to be getting that kind of range in any plane. It would be great, but I can't see it happen in normal use. If I can get 1 mile I'm more then happy.

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